OSTEOLOGY 39 



from the body of the vertebra project lateral processes, and anterior 

 and posterior oblique processes. 



All cervical vertebrae except the atlas and the axis are made up of 

 the following parts: a body, or centrum, a neural canal, a neural 

 arch, a superior dorsal, or neural spine, or neurapophysis, which 

 in most cervical vertebrae is only slightly developed, two oblique 

 processes, or zygapophyses, two transverse processes, or diapophyses 

 (Fig. io,No. 12) and in some vertebrae two tubercles, or anapophyses 

 above the posterior zygapophyses. The prezygapophyses are 

 directed upward and inward; the postzygapophyses are directed 

 downward and outward. The inferior spines are only well developed 

 in the last two or three cervical vertebrae. 



Between vertebral segments, except the central sacral portion, on 

 each side, there is an intervertebral foramen (Fig. 11, No. A, 4), 

 through which pass the spinal nerves. In the central portion of the 

 sacrum where the vertebrae have fused, there are two foramina on 

 each side for each original vertebra, one located above the other, 

 the upper giving passage to the sensory branch, the lower to the 

 motor branch of the nerve. 



The Dorsal Vertebrae (Fig. 4, No. 23; Fig. ii, A). Location. — 

 The dorsal, or thoracic vertebrae, or vertebras thoracicales, aid in 

 forming the roof of the chest cavity. 



Description. — The dorsal vertebral section is made up of seven 

 vertebrae, with strong short bodies. The first and sixth ' dorsal 

 segments articulate as do the cervical, by the bodies and oblique 

 processes. (Fig. 11, No. A, $, illustrates the oblique processes.) 

 The seventh dorsal is fused with the first lumbo-sacral vertebra. 

 The second to the fifth inclusive of the vertebrae are fused together, 

 and the superior and inferior spinous processes are fused into a 

 prominent plate-like ridge. 



The transverse processes of the dorsal vertebrae, from the second to 

 the sixth, are well developed and are bridged over with a thin layer of 

 bone. The ventral spines are partly fused and form a very promi- 

 nent and continuous ridge. (Fig. 11, No. A, i, shows the fused 

 superior spines; No. 2, the fused inferior spines; and No. 4, the inter- 

 vertebral foramina.) 



The Lumbo-sacral Vertebrae (Fig. 5, Part II, No. 4). Loca- 

 tion. — The fused lumbo-sacral section of the spinal column forms 

 the roof of the pelvic cavity. 



Description. — The lumbo-sacral region consists of fourteen verte- 



